A chance observation has drawn my attention to the different variants existing for the Primus 230. Above are my two 230 tanks, so what is the difference? In fact all but one of the points of difference are already there to be seen amongst the gallery examples. But only one has been specifically commented on. And that is the bun-footed version posted by @Takeshi (here). Takeshi's bun-footed 230 also had 'PRIMUS' incuse on the burner top and a pump tube cap with the Linqvist's Patent legend. This was presumably the earliest issue of the 230. It is the slightly later 230s with tubular feet (as shown above) and without the Linqvisit's Patent legend on the pump tube cap that have now caught my attention. The three main difference I've noticed between mine are first, that one has 'PATENT'on the tank top beside 'Made in Sweden', and the other doesn't: c/f this other example and this one. In addition I now notice that there are 2 further differences between the 'PATENT' and plain 'Made in Sweden' versions. The 'PATENT' version has an 'AKTIEBOLAGET PRIMUS' pump tube cap, whereas the other has a Primus Made in Sweden cap: And finally the tank base stampings are also different, with the 'PATENT' version having a simpler rendition of the company designation, as well as the use of different fonts: The other tank markings remained the same on both:] It is interesting to note too that on these versions the original burners now had the #PRIMUS# name in relief, not incuse as with the even earlier bun-foot 230s: Now it may be just coincidence, but, all of the other gallery examples of the 'PATENT' tank type, like mine, were all sold in Swedish provenance badged tins of this sort: On the other hand the versions that are without the word 'PATENT' on the tank top were all supplied in tins with the badge legend reading 'Primus Compact Outfit'. The 3 variants discussed above are all from the pre-1911 period. Then in 1911, along with the introduction of a date coding letter, the tank base marking was also further revised with 'AKT.BOL.' reduced to 'A/B', see the illustration in this post.